Impedance control applied in an exoskeleton robot for the knee joint

• Grant number: 25/06527-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: August 01, 2025
• End date: July 31, 2026
• Field of knowledge: Engineering - Electrical Engineering
• Principal Investigator: Felix Mauricio Escalante Ortega
• Grantee: Marina Jacili Ramalho
• Host Institution: Instituto de Ciência e Tecnologia. Universidade Estadual Paulista (UNESP). Campus de Sorocaba. Sorocaba , SP, Brazil

Abstract

Impedance control techniques have been extensively applied in wearable robotic devices that maintain physical contact with the human body, particularly in motor assistance and rehabilitation contexts. These methods have gained significant attention in the control and robotics literature due to their ability to regulate physical interaction, thereby enabling safe and efficient energy exchange between the robot and the user during movement tasks. Conventional control approaches based solely on force or position have shown limitations in ensuring stability and performance in human-robot interaction. This limitation stems from the need to consider the coupled relationship between force/torque and velocity to account for natural variations in human joint behavior. Furthermore, human dynamics are inherently uncertain and highly variable, often subject to abrupt changes in movement patterns and force magnitudes, which can compromise the accuracy of fixed dynamic models. In this context, this work aims to investigate, model, and implement impedance control strategies for the human knee joint in interaction with a robotic exoskeleton. The proposed methodology includes the development of a physical human-robot interaction model and the analysis of joint impedance variations across different movement tasks. The study also includes a systematic review of exoskeleton technologies, the theoretical foundations of impedance control, and key concepts of human biomechanics, aiming to design a safe and adaptable control architecture suited to diverse user profiles and operational scenarios.